This invention relates generally to inspection systems and methods. More particularly, this invention relates to eddy current inspection systems and methods for inspection of case hardening depths of parts.
Parts, such as crankshafts, valves, gears, piston cylinders are often subjected to heat treatment and carburization to produce case hardening layers on surfaces thereof so as to improve resistance to wear. Different parts generally have different requirements for case hardening depths of the case hardening layers thereon. Thus, it is necessary to perform inspection to determine whether the case hardening depths on such parts are suitable for quality control.
Nondestructive evaluation (NDE) techniques are being pursued to inspect case hardening depths of parts. Since electrical conductivity and magnetic permeability in case hardening regions are different from those in other regions, eddy current inspection techniques can be employed to inspect the case hardening depths of the parts.
In some applications, eddy current methods are used to inspect the case hardening depths of cylindrical objects using encircling probes. However, because the eddy current probes are mounted around the parts, they may merely provide information about average case hardening depths of such parts instead of local information. In addition, such eddy current probes are generally used for inspection of case hardening depths of cylindrical parts, and may not be suitable for inspecting case hardening depths of parts having other shapes.
Therefore, there is a need for a new and improved eddy current inspection system and method for inspection of case hardening depths of parts.